This invention relates to diblock and triblock copolymers. The diblock copolymer has a first block comprising a polyalkylene oxide and a second block consisting essentially of glycolic acid ester and trimethylene carbonate linkages.
The triblock copolymer has a middle block obtained by removing both terminal hydroxyl hydrogens from either a homopolymer of ethylene oxide, or from a copolymer of ethylene oxide and a cyclic ether. Alternatively, the triblock copolymer has a middle block obtained by removing both terminal hydroxyl hydrogens from a copolymer of a first cyclic ether selected from the group consisting of ##STR3## wherein x is 2 to about 9, and a second cyclic ether selected from the group consisting of ##STR4## wherein y is 1 to about 9 and R is a C.sub.1 to C.sub.6 alkyl group.
The diblock and triblock copolymers of this invention are preferably bioabsorbable. They are useful as a coating, and/or as a lubricant, for example as a lubricating finish from a braided multifilamentary material. The diblock and triblock copolymers of this invention are also useful as a hydrogel, for example as an ingredient in a medical or surgical device or in a pharmaceutical composition.
A diblock copolymer has been invented. The copolymer has a first block comprising a polyalkylene oxide and a second block consisting essentially of glycolic acid ester and trimethylene carbonate linkages. In one embodiment, the polyalkylene oxide block is from 5 to 25 percent by weight of the copolymer. In another embodiment, the number average molecular weight of the polyalkylene oxide block is from about 4,000 to 30,000. In yet another embodiment, the polyalkylene oxide block is derived from a polyalkylene oxide terminated on one end by a C.sub.1 to C.sub.6 alkyl group and on the other end by a hydroxyl group.
In a specific embodiment of any of the above embodiments, the polyalkylene oxide block is derived from a homopolymer of ethylene oxide. In another specific embodiment of any of the above, the polyalkylene oxide block is derived from a block or random copolymer of ethylene oxide and a cyclic ether. In a more specific embodiment, the cyclic ether is selected from the group consisting of ##STR5## wherein x is 2 to about 9, y is 1 to about 9 and R is a C.sub.1 to C.sub.6 alkyl group.
In yet another specific embodiment, the polyalkylene oxide block is derived from a block or random copolymer of a first cyclic ether selected from the group consisting of ##STR6## wherein x is 2 to about 9, and a second cyclic ether selected from the group consisting of ##STR7## wherein y is 1 to about 9 and R is a C.sub.1 to C.sub.6 alkyl group.
In a more specific embodiment (to the above specific embodiments), a bioabsorbable diblock copolymer has been invented. The inherent viscosity of the copolymer, as measured at 30.degree. C. for a 0.5% (w/v) solution in chloroform or methylene chloride, is 0.25 to about 1.50 dl/g.
A triblock copolymer has also been invented. The triblock copolymer is useful in nonfiber form. The middle block is obtained by removing both terminal hydroxyl hydrogens either form a homopolymer of ethylene oxide, or from a block or random copolymer of ethylene oxide and a cyclic ether. In one embodiment, the cyclic ether is selected from the group consisting of ##STR8## wherein x is 2 to about 9, y is 1 to about 9 and R is a C.sub.1 to C.sub.6 alkyl group.
Further, an alternative triblock copolymer has been invented. The alternative triblock copolymer is useful in nonfiber form. The middle block is obtained by removing both terminal hydroxyl hydrogens from a block or random copolymer of a first cyclic ether selected from the group consisting of ##STR9## wherein x is 2 to about 9, and a second cyclic ether selected from the group consisting of ##STR10## wherein y is 1 to about 9 and R is a C.sub.1 to C.sub.6 alkyl group.
In a further embodiment of any of the above embodiments, each end block of the triblock copolymer consists essentially of glycolic acid esters and trimethylene carbonate linkages. In a specific embodiment, the middle block is from 5 to 25 percent by weight of the copolymer. In a more specific embodiment, the number average molecular weight of the middle block is from about 4,000 to 30,000.
In a most specific embodiment (to the above specific embodiments), a bioabsorbable triblock copolymer has been invented. The inherent viscosity of the copolymer, as measured at 30.degree. C. for a 0.5% (w/v) solution in chloroform or methylene chloride, is 0.25 to about 1.50 dl/g.